Angiography is a procedure used in the detection and treatment of abnormalities or restrictions in blood vessels. During angiography, a radiographic image of a vascular structure is obtained by injecting radiographic contrast material through a catheter into a vein or artery. The vascular structures fluidly connected with the vein or artery in which the injection occurred are filled with contrast material. X-rays are passed through the region of the body in which the contrast material was injected. The X-rays are absorbed by the contrast material, causing a radiographic outline or image of the blood vessel containing the contrast material. The X-ray's images of the blood vessels filled with the contrast material are usually recorded onto film or video tape and are displayed on a fluoroscope monitor.
During angiography, after a physician places a catheter into a vein or artery, the angiographic catheter is connected to either a manual or an automatic contrast injection mechanism. A typical manual contrast injection mechanism includes a syringe and a catheter connection. The user of the manual contrast injection mechanism adjusts the rate and volume of injection by altering the manual actuation force applied to the plunger of the syringe.
Automatic contrast injection mechanisms typically involve a syringe connected to a linear actuator. The linear actuator is connected to a motor, which is controlled electronically. The operator enters into the electronic control a fixed volume of contrast material and a fixed rate of injection. There is no interactive control between the operator and the machine, except to start or stop the injection. A change in flow rate occurs by stopping the machine and resetting the parameters.
Improvements to controlling an injection mechanism are desirable.